Compositions and methods using reduction-sensitive vat dyes and inorganic nitrites



Patented Apr. 10, 1951 COMPOSITIONS AND REDUCTION SEN AND INORGANICNITRITES Jerry M. MeccoySomerville, N. .L, assignor to American CyanamidCompany, .N. Y., a corporation of Maine No Drawing. Application November30, 1949,

Serial No. 130,356

16 Claims. (Cl. 8-35) 1.. This invention relates to an improved methodof vat dyeing with dyes which show a tendency to over-reduce at hightemperatures.

7 In the past, there has arisen a considerable problem with respect to alarge number of vat dyes. These dyes are-sensitive to high temperaturevats. The sensitivity appears to be due primarily to over-reductioncaused by the hydrosulfite, or other strong reducing agent which is anessential part of any vat dye bath. It is possible and, in case of somedyes even probable that other reactions take place and result indecomposition which is not, strictly speaking, an over-reduction. Thenet effect is that these sensitive dyes, of which the anthraquinonedihydro'azines are typical, have required low temperature dyeingconditions which preclude the rapid dyeing which is possible at highertemperatures and whichhas made various continuous and semi-continuousprocesses possible. High temperature dyeing usually improves dyepenetration and/or levelness, particularly with such fabrics as nylon.In referring to a dye bath, it should be understood that we areconsidering the situation at the time the dye is afiixed to the fiber.In many processes, the dyestuff is present in a dye bath or vat insolution in the form of its reduced leuco compound and the goods areintroduced into this bath. In other processes, such as,

for, example, pigment dyeing processes, whichlend themselves tocontinuous and semi-continuous processes of the package dyeing variety,the dyestufi may be originally incorporated loosely in the fiber in theform of a pigment and then reduced by the dye bathwhich contains onl thereducing constituents and the caustic alkali which is necessary. In sucha case, the dye bath at the fiber includes the dyestuff, but includes itactually in position in the fiber. Throughout this case, the term dyebath will be used to cover both types of situation.

Acsording to this invention, it has been found that the sensitivity ofthe dyes to over-reduction at elevated temperatures can be avoided anddyeings of greater strength and brightness obtained if the dye bathcontains a soluble inorganic nitrite. The ordinary soluble nitrites,such as alkali and alkaline earth metal nitrites, may be used. Becauseof its cheapness and excellent results obtained, sodium nitrite is thepreferred member.

The amount of nitrite to be used is not critical; but there is, ofcourse, a minimum below which usefulimprovement doesnot result. Thispractical minimum is about one-quarter the weight SITIVE VAT troubleuntil the i temperature"approaches much OFFICE j f New York, v

of the dyestufi. When more nitrite is added, re-' sults improve; butsoon a practical optimum is reached at from 1.5-2 parts of nitrite perpart of dye, beyond which additional nitriteusually does not giveresults which warrant the additional cost. However, as much as 16 ormore parts of nitrite per part of dyestufi may be used with nodeleterious results. The additional cost, however, is not warranted, andsuch procedures are economically unattractive. 1

It is not known just how the nitrite-acts.- It seems probable thatonefa'ctor may be a kind of reduction-buffer action preventingfov'erjreduction in this type of reaction There "s; however, strong evidenceto-sh'owthat this isl'not the only factor, because other oxidizingagents,- such as inorganic nitrates or organic nitrites and nitrates,will not give the improved results of the inorganic nitrites of thepresent invention. It would seem logical, therefore, that there is atleast one and maybe a number of other factors involved in the operationof the present inven tion. Accordingly, it is not intended to limit theinvention to any particular theory 10f action, the above discussionbeing given purely; as the best partial explanation of certain possible:fac

tors, as far as present knowledge goes. 7

The various dyestuif s'which are sensitive to overreduction at hightemperature do not all. show the same sensitivity. Some are much, moresensitive than others, or rather, show bad results at much lowertemperatures. The 'anthraqui none dihydroazines are among the mostsensitive, and some of them give bad results at'dyeingtemperatures aslow as F. Others do not" show deleterious results; until temperatures of-160 F. are reached; and some do not give closer to theboiling point of'water. I

The optimum dyeing temperature with-each} dye will besomewhat'different; and it'is not go's-' sible, therefore, to give anysingle temperatur which is equally effective with all dyes. How ever, itis an important factor of the present in-' vention that, in most cases,dyeing can be effect-f ed at temperatures approaching the boiling pointof water without'material loss of strength of: brilliance; and manysensitive dyestufis can, therefore, be used at high temperatures, whichmakes the present invention of particular signifi canoe where such hightemperature dyeing s important from the standpoint of savings in time,"use of continuous or semi-continuous dyeing processes, and'th'elikej V eAnother advantage of thepresent invention" dyeing with sensitive dyespractically unattractive before the present invention, even though thedyes were not seriously over-reduced if a certain definite temperaturelimit were not exceeded. Extremely critical supervision of any chemicalprocess adds cost and is a disadvantage. It is particularly unfortunatein dyeing operations where exact temperature control, at all times, isoften a difficult thing to achieve. When the present invention is usedonly reasonable care need be exercised to prevent very great temperaturechanges.

dyed yarn was then removed and the excess dye liquor extracted from theyarn. The remaining dye on the yarn was then oxidized for five minutesin the air at room temperature, after which it was immersed in anoxidizing solution consisting of 0.1% sodium peroxide (100 volumes) and0.1% glacial acetic acid solution for minutes at 140 F. The dyed yarnwas then rinsed in In addition to the anthraquinone dihydroazinesreferred to above, a large number of other vat dyestuffs showsensitivity to high temperature dyeing. Typical dyestuffs are thefollowing: Dinitro dibenzanthrone, oxy nitro dibenzanthrone, 1:4di-benzoylamino-anthraquinone, i,4'-dihydroxy indanthrene,2('1-aminoanthraquinonyl-2)-4,5,beta anthraquinone-oxazole,di-dibenzanthronylamino-di-alpha anthraquinonylamino pyranthrone,3,4,8,9 dibenzpyrene 5,10 quinone, 1,1',4,1"-trianthrimide carbazole.Other dyestuffs are those having the Color Index Numbers: 1135, 1106,1112, 1113, 1114, 1151, 1162, 1102, 1099, 1173, 1150, 1163 and 1109.

It is an advantage of the present invention that it may be applied inseveral ways. For example, vat dye baths can be made up by adding all ofthe ingredients, that is dye, alkali, reducing agent and nitrite, toproduce a finished bath. Another method which has the practical advantage of making it unnecessary for the dyer to control closely theproportion of all ingredients going into the dye bath, is to blend withthe dyestuif a suitable amount of nitrite to form a powder Or a paste.This blend, which constitutes a new article of manufacture includedwithin the scope of the present invention, may be sold. The dyer maythen prepare. his bath with the dyestuff blend, the alkali and thereducing agent in any convenient order.

The invention will be. illustrated in greater detail in conjunction withthe following specific examples. Parts are by weight. I

Example 1 Three parts of the dye having Color Index No. 1113 andcontaining about 18.5% real dye were mixed with 3 parts of sodiumnitrite. This mixture was then added to 1170 parts of water at 160 F. Tothis was added 35 parts of 30 Be. sodium hydroxide, after which thetemperature was again adjusted to 160 F., and nine parts of sodiumhydrosulfite added and dissolved. The temperature was maintained at 160F. for minutes, after which time the color was reduced. This will bereferred. to as the standard leuco solution. 400 parts of this reduceddye solution was then transferred to a separate dye beaker.

parts of natural cotton yarn were pre-wet with approximately solution ofa pine oil soap, the excess removed by squeezing, and the yarn thenentered into the 400 parts of reduced vat dye and dyed at 160 F. for 15minutes, The

warm water to remove the excess glacial acetic, soaped at the boil for10 minutes in 0.1% soap and 0.1% soda ash solution, rinsed and dried.

A control dye bath was prepared exactly like the above except the sodiumnitrite was omitted. This was used to make a control dyeing using thesame procedure as above. The yarn dyed in the bath containing the sodiumnitrite was approximately stronger, redder, and brighter than thecontrol dyeing.

Example 2 The standard leuco solution prepared in Example 1 wasmaintained at a temperature of F. for an additional 20 minutes, afterwhich 6 parts of 30 Be. sodium hydroxide and 2 parts of sodiumhydrosulfite were added and the temperature maintained at 160 F. for anadditional 40 minutes, making a total standing time of '75 minutes.- 400parts of this standard leuco solution was then removed and transferredto a dye beaker.

20 parts of cotton yarn, pre-wet as in Example 1, was then entered intothe dye bath and dyed as in Example 1. The same procedure was used withthe control dyebath, again having a standing time of 75 minutes, afterwhich 20 parts of cotton yarn, pre-wet as above, was entered and dyed asabove.

The yarn dyed from the bath containing the sodium nitrite after the dyebath had stood for '75 minutes was similar in strength and shade to theyarn dyed in the bath containing the sodium nitrite in Example 1.However, the yarn dyed in the control bath in Example 2 was now a dirtgray and not a bright red-blue. This indicates a chemical change of thedye in the control bath in which no sodium nitrite was present when thedyeing was made after the bath had stood at 160 F. for '75 minutes.

Example 3 The procedure of the preceding two examples was repeatedexcept the temperature was raised from 150 F. to F. Again the yarn dyedin the bath containing the sodium nitrite was blue, bright and strong,whereas the yarn dyed in the control bath was a dirty gray and unfit forpractical use.

Example 4 The procedure of the preceding example was repeated exceptthat the temperature was raised to about 212 F. Again the dyeing made inthe dye bath containing the sodium nitrite was a commerciallysatisfactory blue whereas the yarn dyed in the control dye bath was dyeda dirty gray.

Example 5 10 parts of cotton yarn were dyed in a bath containing about0.09 part of the real dye having Color Index 1113, three parts of sodiumhydroxide, three parts of sodium hydrosulfite, 1.5 parts of sodiumnitrite in 400 parts of water. The bath was heated for five minutes atabout 200 F. during which time the vat dye was reduced, after which thecotton yarn was entered and dyed for 60 minutes at about 200 F. The dyedyarn was then removed, and the excess dye liquor extracted from theyarn. The remaining dye on the yarn was then oxidized for five minutesin the air at room temperature, after which it was immersed in anoxidizing solution consisting of 0.1% sodium peroxide (100 volumes) and0.1% glacial acetic acid solution for ten minutes at 140 F. The dyedyarn was then rinsed in warm water to remove the excess acid, soaped atthe boil for ten minutes in 0.1% soap and 0.1% soda ash solution, rinsedand dried. The color was a bright blue and the yarn was dyed a fullshade.

A second dyeing was made like the above except the 1.5 parts of sodiumnitrite were omitted from the dye bath. The material dyed in this bathwas a dull, dirty gray.

Example 6 The procedure of the preceding example was repeated except 1.5parts of the sodium nitrite were used and the dye had Color Index No.1102. The yarn dyed in the bath containing the sodium nitrite wasstronger than that dyed in the control bath.

Example 7 The procedure of the preceding example was repeated except thedye oxy-nitro-dibenzanthrone was used. The color of the yarn dyed inthis bath was stronger than that of the yarn dyed in the control bath,especially when aftertreated.

Example 8 The procedure of the preceding example was repeated exceptthat the dye having Color Index No. 1135 was used. The yarn dyed in theoath containing the sodium nitrite was stronger and brighter than theyarn dyed in the control bath.

Example 9 Example 10 The procedure of Example 5 was repeated except thatthe dye having Color Index No. 1106 was used. The yarn dyed in the bathcontaining the sodium nitrite was much stronger and brighter than thatdyed in the control bath.

Example 11 The procedure of Example 5 was repeated except that the dyehaving Color Index No. 1151' was used. The yarn dyed in the bathcontaining the sodium nitrite was superior to that dyed in the controlbath.

Example 12 The procedure of the preceding example was repeated exceptthat the dye having C'olorIndex No. 1162 was used. The results weresatisfactory.

Example 13 The procedure of Example 5 was repeated except 1.5 parts ofKNO2 were substituted for the 1.5 parts of NaNO2. Cotton yarn dyed inthis bath was a bright blue, whereas the yarn dyed in the control bathwas a weak gray.

Example 14 Example 15 The procedure of Example 5 was repeated exceptthat the dye 1,2,6,'7-dibenzpyrene-3,8-quinone was used.

Example 16 The procedure of the repeated except the dye oarbazole wasused.

preceding example was 1,1 ',4,1' -trianthrimide Example 17 The procedureof Example 5 was repeated except that only 0.025 part NaNOz was added.Cotton yarn dyed in this bath showed some loss in blue shade but wassuperior to the control sample.

' Example 18 The procedure of Example 5 was repeated using the dye6,6-dichl0ro-4,4-dimethyl-2;2'-bis thionaphthene indigo and theresulting dyeing was commercially satisfactory.

F. for 15 minutes and the resulting ascetic Example 20 of 177 Britishgum (Stein Hall) in 5,000 parts of water and the mixture was heated withcontinuous stirring until the temperature reached about 185 F. Heatingwas continued for about 1 hours after which 450 parts of powderedpotassium carbonate and/150 parts of powdered sodium carbonatewere'added and the mixture stirred until the carbonates dissolved.Heatin was discontinued but stirring was continued until the temperaturereached approximately 150 F. at which time 700 parts of sodiumsulphoxylate were dissolved therein, 600 parts of glycerine were added,and the paste bulked to 10,000 parts. Stirring was continued until thepaste cooled to room temperature.

A control printing color paste was prepared as the above except thesodium nitrite was omitted.

Pieces of 80 x 80 bleached, unmercerized cotton fabric were printed,air-dried, aged in a steam ager, oxidized, rinsed, soaped at the boil ina 0.1% soap solution for five minutes, rinsed again, and ironed dry.

Prints made from the color paste which contained the sodium nitrite werea bright blue shade of good strength, while prints made from the controlpaste were a dull dirty gray.

Example 21 Example 22 The procedure of the preceding example wasrepeated except :the dyeing time was one hour and 45 minutes. The yarndyed in the bath containing the sodium nitrite was approximately 15%stronger, slightly redder and slightly brighter when dyed for thislonger period.

Example 23 The procedure of Example 21 was repeated except the dye wasreduced and dyed at 140 F. The yarn dyed in the bath containing thesodium nitrite was about 25% stronger, brighter and redder than thecontrol dyeing.

Example 24 a The procedure of Example was repeated ex cept that rayonwas used and the results were substantially the same as for cotton.

Example 25 The procedure of the preceding example'was repeated-exceptlinen was used. The dyeing made in the bath containing the nitrite wasbright blue while the dyeing made in the .control bath was a dirty gray.1

Example 26 The procedure of Example 5 was repeated .except a nylon piecewas used and the dye bath temperature was 212 F. The piece dyed in thebath containing the sodium nitrite was commercially satisfactory.

Example 27 A dyeing was made at a temperature of about 250 F.(approximately 50 pounds pressure) on 2.5 parts of bleached unmercerizedcotton in the apparatus described in U. S. P. 2,405,167, using a dyebath of 300 parts liquor containing 0.09 part of real dye having ColorIndex 1113, one part of sodium nitrite, five parts of sodium hydroxideand six parts of sodium hydrosulfite. The piece was dyed for twominutes. The bath was then flushed with water to the sewer, the dyeingremoved, oxidized and finished as in Example 1'. A good, strong, brightblue shade was obtained even at this high temperature.

A control dyeing, in which no sodium nitrite was present, but otherwisemade as above, was dyed a dull gray shade.

Example 28 Example 29 500 parts of No. 20s, 2-p1y, natural cotton yarnin package form were wet out with 7,000 parts of a /1;% solution of asurface-active anionic material, which had been preheated to 190% F. Thepackage was then dyed in a dye bath containing nine parts of real dyehaving Color Index 1113, 15. parts of.a surface-active anionic materialand 22.5 parts of sodium nitrite in 1,000 parts of water, making a totaldye bath volume of 8,000 parts.

The dye dispersion was first heated to 190 R, and then circulatedthrough the wet-out package for ten minutes, after which 200 parts of 30Be. sodium hydroxide, which had been preheated to 190 F., were added tothe dye bath and circulated for five minutes, after which 50 parts ofsolid sodium hydrosulfite were added and circulated for 25 minutes. Thespent dye bath was then flushed with water from the machine, the dye wasoxidized with 2 of LOO-volume hydrogen peroxide for 10 minutes at F.,after which the package was soaped, rinsed and dried. A bright bluedyeing having excellent levelness was obtained.

A control dyeing was made in the same manner except the sodium nitritewas omitted from the dye bath. The package dyed in the control bath wasan uneven, dull, greenish-blue shade with no commercial value.

Example 30 900 parts of the real dye, having Color Index No.".1106, wereground and dry blended with 250 parts of potassium nitrite. Ten parts ofcotton were dyed in a bath containing 0.115 part of this blend, 3 partsof sodium hydroxide, and 3 parts of sodium hydrosulfite in 400 parts ofwater using the general method of Example 5. The resultant dyeing was'bluer and brighter than a control dyeing made from a bath containingthe same amount of real dye, alkali and hydrosulfite but omitting thepotassium nitrite.

Example 31 450 parts of the real dye used in Example 16 were ground anddry blended with 7,500 parts of sodium nitrite. Ten parts of cotton yarnwere dyed in a bath containing 1.6 parts of this blend.

3 parts of sodium hydroxide and 3 parts of sodium hydrosulfite in 400parts of water using the general method of the preceding example. Thedye-- ing obtained from this dye bath was stronger and brighter thanthat obtained from a control dye bath in which no sodium nitrite waspresent.

Example 32 960 parts of the dye having Color Index No. 1113 and 2,400parts of sodium nitrite were ground and dry blended to give ahomogeneous mixture. Ten parts of rayon yarn were dyed in a bathcontaining 0.35 part of this blend, 3 parts of sodium hydroxide, and 3parts of sodium hydrosulfite in 400 parts of water by the general methodused in Example 5, and the results were similar to those obtained inExample 5.

Example 33 brighter than that made from a control dye bath in which nolithium nitrite was present.

Example 34 462.5 parts of the 20% wet press cake containing about 92.5parts of the dye having Color Index No. 1113 and 400 parts of sodiumnitrite were stirred together and then made up to 1,000 parts withwater. One part of this paste was substituted for the one part of thepaste of the preceding example, the dyeings were made a in the precedingexample, and the results were satisfactory.

Example 35 The procedure of the preceding example was repeated exceptpart of the water needed to bring the paste to 1,000 parts was replacedwith glycerine to give a glycerine content of 0% on the final weight.Dyeings made with pastes containing glycerine were quite satisfactory.

Example 36 The proceudre of the preceding example was repeated exceptthe glycerine was replaced by ethyleen glycol. Cotton yarn dyed withthis paste is commercially satisfactory.

Example 37 The procedure of the preceding example was repeated exceptthe wet press cake was dispersed with parts of the sodium salt ofdisulfo-dinaphthyl methane. the humectant then added and the paste madeup to 1,000 parts. Cotton yarn dyed in a bath containing one part ofthis paste but otherwise dyed as in Example 34 gave satisfactoryresults.

I claim:

1. A method of vat dyeing fibrous material to which alkali metal saltsof leuco vat dyestuffs substantive with a vat dye which is sensitive tooverreduction at the boiling point of water in an ordinary vatcontaining strong alkali and sufficient reducing agent to maintainreduction of the vat dyestuff, which comprises effecting the dyeing inthe presence of such a bath containing, in addition to the strong alkaliand reducing agent for the vat dyestuff, an amount of an inorganicnitrite at least one-fourth the weight of the real dyestulf.

2. A method according to claim 1 in which the dyestuff is ananthraquinone dihydroazine.

. 3. A method according to claim 2 in which the nitrite is sodiumnitrite.

4. A method according to claim 1 in which the nitrite is sodium nitrite.

5. A method according to claim 1 in which the dyestuff is an anthrimidecarbazole.

6. A method according to claim 5 in which the nitrite is sodium nitrite.

7. A method according to claim 1 in which the dyestuff is a cyanuricchloride derivative of an aminoanthraquinone.

8. A method according to claim 7 in which the nitrite is sodium nitrite.

9. As a new article of manufacture a blend of a vat dyestuff sensitiveto over-reduction at the boiling point of water in a vat dye bathcontain ing strong alkali and sufiicient reducing agent for the vatdyestuff to maintain reduction and an amount of an inorganic nitrite atleast onequarter the weight of the real dyestuff.

10. An article of manufacture according to claim 9 in which the dyestuffis an anthraquinone dihydroazine.

11. An article of manufacture according to claim 10 in which the nitriteis sodium nitrite.

12. An article of manufacture according to claim 9 in which the nitriteis sodium nitrite.

13. An article of manufacture according to claim 9 in which theclyestuif is an anthrimide carbazole.

14. An article of manufacture according to claim 13 in which the nitriteis sodium nitrite.

15. An article of manufacture according to claim 9 in which the dyestuifis a cyanuric chloride derivative of an aminoanthraquinone.

16. An article of manufacture according to claim 15 in which the nitriteis sodium nitrite.

JERRY M. MECCO.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,029,999 Grieshaber Feb. 4, 19362,146,646 Nusslein Feb. '7, 1939 2,383,393 Kienle Aug. 21, 1945

1. A METHOD OF VAT DYEING FIBROUS MATERIAL TO WHICH ALKALI METAL SALTSOF LEUCO VAT DYESTUFFS ARE SUBSTANTIVE WITH A DYE WHICH IS SENSITIVE TOOVERREDUCTION AT THE BOILING POINT OF WATER IN AN ORDINARY VATCONTAINING STRONG ALKALI AND SUFFICIENT REDUCING AGENT TO MAINTAINREDUCTION OF THE VAT DYESTUFF, WHICH COMPRISES EFFECTING THE DYEING INTHE PRESENCE OF SUCH A BATH CONTAINING, IN ADDITION TO THE STRONG ALKALIAND REDUCING AGENT FOR THE VAT DYESTUFF, AN AMOUNT OF AN INORGANICNITRITE AT LEAST ONE-FOURTH THE WEIGHT OF THE REAL DYESTUFF.